Following a shutdown of a turbomachine, e.g., a Gas Turbine (GT) engine, a bowing of one or more components, e.g., the turbine casing, may result, which increases the risk of other components, e.g., the turbine blade tips, rubbing upon restarting the GT. To reduce the rubbing risks, e.g., Direct Air Injection Systems (DAIS) have focused on controlling the top half casing temperature for the mid-frame shell (and all TVC cavities) with good results, provided the DAIS system is operational across the shutdown. An example of this type of DAIS system is described in U.S. Pat. Nos. 8,893,510 and 8,820,091, both disclosures of which are incorporated herein by reference in its entirety for describing the DAIS systems.
However, engine operational disturbances during shutdown do occur, e.g., equipment failures and operational limits resulting in engine trips, which impacts the DAIS operation, and therefore, may increase rubbing risks. Due in part to these disturbances, the DAIS system enforces a time based engine start lockout period, e.g., of approximately 30-50 hours, which limits the ability to restart the GT prior to it achieving a fully cooled condition. This restriction period generally continues until natural convention effects start to diminish and a clearance of any rubbing risks is achieved, resulting in the GT being safe to restart. Consequently, during this restart restriction period, the GT is unavailable for an extended period of time, as the full duration of the restriction period must be achieved, regardless of whether any rubbing risks exist at any point during the lockout restriction period.
Therefore, a need exists for an improved system and method for determining rubbing risks within the GT for safely starting the GT, and independent of the DAIS and any disturbances.